Core and molding sands



Patented June 20, 1950 UNITED CORE AND MOLDING SANDS Lucien Rouzet, Clichy, France, assignor to LImpregnation, Clichy, France No Drawing. Application September 5, 1946, Se-

rial No. 695,045. In France January 24, 1940 Section 1, Public Law 690, August 8, 1946 Patent expires January 24, 1960 It ishighly desirable in foundry work to aaglomerate the core and molding sands by means of an agglomerating agent which on the one hand is completely consumed by the heat of the molten metal, to allow the sand to come out after cooling, and which on the other hand at the temperature of the molten metal is sufficiently plastic to yield to the shrinkage of the metal during its cooling.

The agglomerates at present used in founding do not possess this thermo-plasticity or only possess it to an insufiicient extent. This results i in flaws, which are the cause of considerable wastage.

These disadvantages are avoided according to the invention, owing to the fact that a synthetic resin is used as agglomerant.

A synthetic resin with a basis of amylaceous material is preferably utilized, of the type described in the specification of our co-pending patent application No. 695,044 entitled Improvements relating to synthetic resins.

As described in the said specification, the preparation of this new synthetic resin may, for example, be carried out in the following fashion:

1 kg. of soluble starch is dissolved in 2 liters of 40% formaldehyde. This solution is neutralized, and is heated to 100 centigrade and kept at this temperature for two hours. The solution has then become clear and very fluid. To this solution is added:

200 grams of urea; 75 grams of phenol; 20 grams of carbonate of soda.

The temperature is maintained at 100 for another 15 minutes and then cooling takes place. In this way a coloured liquid is obtained, which is soluble in water and in mineral and vegetable oils,

, but which precipitates in alcohol.

The liquid product thus obtained may be dried in a vacuum, and is then obtained in the form of a hard, translucent material, difiicult to crush, and appearing as a true resin.

This synthetic resin is utilized as an ag- 2 Claims. (Cl. 22-188) glomerant either in solid form or in a more or less 4 syrupy or pasty state.

To prepare the core sand or molding sand according to the invention, it is possible according to a first example to treat the sand with a quantity of 3 to 5% of the said synthetic resin.

According to another example an agglomerant is prepared consisting of a mixture of: 75 kg. of

The procedure will be similar in the case of other synthetic resins such as vinylic resins and the like.

The sands and cores prepared with these agglomerants have the advantage that the agglomerant is completely consumed, whilst providing the requisite thermo-plasticity, so that the castings produced are free from flaws.

More especially the agglomerant with a synthetic amylaceous resin base has the advantage of a low cost.

As in the case of the second example mentioned above, the synthetic resin can be used dissolved in oil.

' Naturally the examples indicated above are only given by way of example. The proportions as well as the ingredients mixed with the synthetic resin may vary according to the problems to be solved; cores may be packed by compressed air, by hand, stripped on plates, in chills etc.

I claim:

1. A foundry composition comprising a body of sand and from 2-5% of a binder consisting essentialiy of a synthetic amylaceous urea phenol formaldehyde resin comprised of substantially more than one half starch, a major portion of the remainder being formaldehyde, with a smaller amount of urea and a still smaller amount of phenol.

2. A foundry composition comprising a body of sand and from 23% of a binder, the major fraction of which binder consists of a synthetic amylaceous urea phenol formaldehyde resin comprised of substantially more than one half starch, a major portion of the remainder being formaldehyde, with a. smaller amount of urea and a still smaller amount of phenol, the remainder of said binder consisting substantially of a siccative oil.

LUCIEN ROUZET.

file of this patent:

UNITED STATES PATENTS Number Name Date 2,121,076 Ellis June 21, 1938 2,148,642 Ricard Feb. 28, 1939 2,203,471 Ray June 4, 1940 2,212,314 Bauer Aug. 20, 1940 2,246,635 Moller June 24, 1941 FOREIGN PATENTS Number Country Date 371,789 Great Britain Apr. 28, 1932 506,770 Great Britain June 5, 1939 515,470 Great Britain Dec. 6, 1939 

1. A FOUNDRY COMPOSITION COMPRISING A BODY OF SAND AND FROM 2-5% OF A BINDER CONSISTING ESSENTIALLY OF A SYNTHETIC ANYLACEOUS UREA PHENOL FORMALDEHYDE RESIN COMPRISED OF SUBSTANTIALLY MORE THAN ONE HALF STARCH, A MAJOR PORTION OF THE REMAINDER BEING FORMALDEHYDE, WITH A SMALLER AMOUNT OF UREA AND A STILL SMALLER AMOUNT OF PHENOL. 